This invention relates to an apparatus for grinding and comminuting wood and other materials, particularly for recycling the materials. In particular, the invention relates to an apparatus which may be provided for a wide variety of heavy-duty grinding processes such as for wood, plastics, paper, aluminum, asphalt, rubber tires, and the like with increased durability, longetivity, and reliability yet essentially without mechanical vibration and at a low noise level.
The invention mainly concerns the type of grinding apparatus known as a rotary grinder in which the material is ground by a combination of shock and shearing effects between the rotating blades of a grinding rotor and blade edge fixed on a frame on which the rotor is carried.
Previously, apparatus have been known commonly referred to as "breakers" which utilize a pair of hollow rotors having a plurality of cutting blades. The rotors are rotated toward a stationary anvil which breaks the material into chunks dropped through grates below the rotors. Typically, the blades are mounted to the rotors by machining out a straight circumferential cut-through on the surface rotor and bolting the blade to the rotor cut-through. While these breakers are suitable for some grinding processes, they lack the structural integrity for other heavy-duty grinding processes. In particular, the rotors of these grinders have been driven with electric motors through gear boxes and these drive arrangements have been problematic. In addition, the horsepower that can be utilized for grinding is limited by the gear box size which becomes prohibitively expensive for large electric motors possessing sufficient horsepower for heavy-duty grinding. Previous apparatus have been provided having a pair of rotors with intermeshing blade teeth typically referred to as "shredders" as illustrated in U.S. Pat. No. 5,285,973. This patent discloses the use of a hydraulic motor rather than the conventional electric motor arrangement. However, an addition coupling is utilized between the output shaft of the hydraulic motor and the shaft of the rotor.
U.S. Pat. No. 5,320,293 discloses a rotary grinder employing blades which are arranged in a pattern on the periphery of a rotor to affect a desired distribution of the material for grinding along the length of the rotor. In this blade pattern, a plurality of identical blades of small lengths with respect to the length of the rotor are mounted on the periphery of the rotor along certain regularly spaced apart generatrix lines. While this pattern may be suitable for its intended purpose, it may not be entirely satisfactory for others such as when utilizing a pair of opposing cutting blade rotors both of which are rotating toward cut edges of an anvil.
U.S. Pat. No. 5,269,355 discloses a cutting wheel for a stump grinder having cutting blades with a pair of opposed cutting edges which may be reversibly utilized by reversing the operation of the cutting wheel. The cutting blades are attached by bolts. U.S. Pat. Nos. 1,423,867 and 526,043 disclose alternate arrangements of mounting cutting blades to single rotor grinders.
Accordingly, an object of the present invention is to provide an improved grinding apparatus for heavy-duty applications for handling load reverses and/or shocks that occur in the grinding of the materials in a comminution process, e.g. grinding down of particles into smaller particles.
Another object of the invention is to provide a precisioned grinding apparatus which may be used in grinding heavy weight or light weight materials into a small size for recycling wherein the precisioned construction provides greater longevity, reliability, and productivity.
Another object of the invention is to provide a grinding apparatus for heavy-duty grinding processes which is constructed to operate essentially without mechanical vibration and at a low noises to provide a highly durable, long lasting grinding apparatus.
Yet another object of the invention is to provide a grinding apparatus having a pair of parallel cutting blade rotors with a plurality of cutting blades which cut against a cutting anvil disposed in a cutting nip of the rotors wherein precision, parallel alignment of the cutting blade rotors, anvil cutting edges, and screen sieve assemblies is provided for reducing waste material to small pieces and particles by repeated cutting.
Another object of the invention is to provide a grinding apparatus having a frame upon which at least one cutting blade rotor and cutting anvil are carried so that a clearance space between the anvil and cutting blade edges may be precisely set to provide comminution of a wide range of materials ranging from wood, metal, and to thin film plastic bags.
Another object of the present invention is to provide a rotary grinding apparatus having high structural integrity by mounting cutting blade rotors and a cutting anvil in solid plate sides in which bearing housings are disposed in close proximity to opposing end faces of the cutting blade rotors so that a tight, in-line direct drive of the cutting blade rotors may be had by means of concentrically mounted hydraulic motors wherein the rotors, rotor journals, bearings, and motor are compactly arranged in an in-line drive arrangement for transmitting high horsepower and torque to the cutting rotors.
Yet another important object of the present invention is to provide a rotary grinding apparatus having solid machined rotors with blade pockets machined in the periphery of the rotor having recessed heels which receive mounting blocks of cutting blades to support and reinforce the cutting blades against cutting.
Another object of the present invention is to provide a rotary grinding apparatus having one or more rows of axially and circumferentially spaced cutting blades arranged in at least one repeat of a diverging pattern wherein the blades diverge outwardly from a central cutting blade in the direction of rotation of the rotor to control the distribution of material along the rotors and the uniform cutting along a cut line along the length of the cutting rotor.